The present invention relates generally to utility meters, and more particularly, utility meters having communication circuits.
Utility meters are devices that, among other things, measure the consumption of a utility generated commodity, such as electric energy, gas, or water, by a residence, factory, commercial establishment or other such facility. Utility service providers employ utility meters to track customer usage of utility generated commodities. Utilities track customer usage for many purposes, including billing and tracking demand for the relevant consumed commodity.
Increasingly, meters employ electronic circuits to both reduce the number of moving parts in the meters and to provide enhanced metering and data collection services. In addition, meters have increasingly employed communication circuits to facilitate remote meter reading. Specifically, a utility meter is typically installed at or near the facility or residence of each customer. Service providers historically have used field technicians or xe2x80x9cmeter-readersxe2x80x9d to obtain usage data from the remotely located utility meters. Manual meter reading, however, imposes significant labor costs and is vulnerable to transportation problems and human error. Consequently, utility meters have been increasingly outfitted with communication circuits to facilitate remote meter reading.
One type of utility meter, the electrical utility meter, includes electronic circuits that automatically generate and store electrical energy consumption information. The electrical utility meter may also include circuits that communicate the electrical energy consumption information to a remote device to achieve the aforementioned remote meter reading operation. The remote device may be part of a centralized data processing arrangement that collects energy consumption information from a multitude of meters via one or more of various hard-wired and/or wireless communication networks such as, for example, telephone networks and radio networks. Such arrangements can significantly reduce (or eliminate) the need for manual meter reading of large numbers of meters located over wide areas.
In general, electrical utility meters having such communication capabilities may be divided into three parts: a sensor part, a measurement part, and a communication interface. The sensor part includes primarily analog circuitry in the form of sensor devices that are connected to the electrical system of a facility, and more particularly, to the power lines. The sensor devices generate energy consumption signals that are indicative of the voltage and current in the power lines. The measurement part includes primarily digital circuitry that receives and processes the energy consumption signals generated by the sensor part. As a result, the measurement part generates metering data representing, for example: watt-hours, volt-amps (xe2x80x9cVAsxe2x80x9d), reactive volt-amps (xe2x80x9cVARsxe2x80x9d) and other information that quantifies the power consumed by the facility.
The communication interface includes digital and/or analog circuits for transmitting the metering data and/or diagnostic data to a remote device. The communication interface may also receive commands from a remote device regarding desired transmissions and/or operating modes. The communication circuits of meters that communicate with a centralized data processing system typically employ digital modems. Digital modems are capable of relatively high data rates, and may be used to effectuate communication over a public switched telephone network (xe2x80x9cPSTNxe2x80x9d). Accordingly, meters employ digital modems to allow a substantial number of meters to communicate information to a central location in any given time period.
One drawback to the use of digital modems in meters arises in the operation of the meter during a power outage. The electronic circuitry within the meter requires bias power to operate. The bias power is often provided by a power supply within the meter, which derives its power from the AC power lines. In the event of an AC power interruption (including but not limited to any situation in which the AC electrical power received from the power lines is greatly reduced or completely absent, whether by design or by accident) the circuitry within the meter loses the bias power derived from the AC electrical power. If all of the bias power to the circuitry is lost, then the circuitry cannot perform metering and reporting functions. Consequently, a secondary power source (for example, a battery) is typically employed to enable the meter to perform certain metering and reporting operations during a power outage.
The drawback of using digital modems for meter communications is that the operation of a digital modem generally consumes a substantial amount of power. As a result, if a power interruption occurs and such a meter is operating from a battery or super-capacitor back-up power source, the operation of the modem may consume the back-up power source at an undesirably rapid rate. Such rapid power source consumption can leave little or no back-up power available for sustaining other desired operations of the meter (such as, for example, time keeping operations) during an interruption in the primary power. Also, where a battery is used as the back-up or secondary power source, the high power consumption hastens the inevitable inconveniences of servicing and/or replacing the expended battery.
Accordingly, there is a need to reduce the high power demand that an electrical meter""s communications operations make on the meter""s secondary power source when the primary electrical power to the meter is interrupted.
The present invention fulfills the above need, as well as others, by providing a communication system for a utility meter that includes primary and secondary communication circuits, where the secondary communication circuit is employed during power interruptions and the primary communication circuit is employed during normal circumstances. The primary communication circuit preferably provides relatively high speed communication functionality under normal circumstances (i.e. when there is no interruption of primary electrical power to the meter). By contrast, the secondary communication circuit, which preferably consumes less power and may have a lower data rate, is employed in the event of an interruption in the primary electrical power. Because little data need be transmitted in the event of a power interruption, the reduced data rate of the secondary communication circuit is sufficient. Advantageously, such a low data rate is readily accomplished using a low power circuit.
In accordance with one embodiment of the present invention, a communication system for a utility meter is provided, wherein the utility meter includes a primary power supply operable to receive a primary electrical power from a primary power source and generate a primary bias power therefrom. The communication system includes a primary communication circuit operable to effectuate external communications when said primary electrical power from the primary power source is present. The communication system further includes a secondary communication circuit operable to effectuate external communications when said primary electrical power from the primary power source is interrupted.
In accordance with another embodiment of the present invention, a utility meter having a communication system is provided. The utility meter includes a source of commodity consumption signals. The utility meter further includes a measurement circuit operable to generate metering data from the commodity consumption signals. The utility meter also includes a primary power supply operable to receive a primary electrical power from a primary power source and generate a primary bias power therefrom. Furthermore, the utility meter includes a primary communication circuit operable to effectuate external communications when said primary electrical power from the primary power source is present. The utility meter also includes a secondary communication circuit operable to effectuate external communications when said primary electrical power from the primary power source is interrupted.
In accordance with another embodiment of the present invention, a power interruption communication method for a utility meter is disclosed, wherein the utility meter includes a primary communication circuit for effecting external communication, the primary communication circuit operably connected to receive primary bias power from a primary power supply, the primary power supply having an arrangement for obtaining a primary electrical power from a primary power source. The power disturbance communication method includes detecting an interruption in the primary electrical power from the primary power source. The power disturbance communication method further includes reducing an amount of operation of the primary communication circuit when the primary electrical power from the primary power source is interrupted. The power disturbance communication method further includes increasing an amount of operation of the secondary communication circuit when the primary electrical power from the primary power source is interrupted.
By utilizing the secondary communication circuit to effectuate communications between the meter and the remote device when the primary electrical power to the meter from the primary power source is interrupted, the demands placed on whatever secondary power source the meter employs are reduced.
The above discussed features and advantages, as well as others, may be readily ascertained by those of ordinary skill in the art by reference to the following detailed description and accompanying drawings.